Understanding Fire Blight

by Guest Author on 09/03/2010

[Guest blog post by Judy]

Hello, my fellow fruit-lovers!

It has been very cool and wet here this past spring and summer. Of course, these are ideal conditions for fungal and bacterial diseases to infect fruit trees, as well as other trees and shrubs. Since the weather can stimulate certain bacterial diseases, I thought you backyard fruit gardeners might like some background on, and ideas on how to control, one of the most prevalent bacterial diseases affecting fruit trees (like apples, pears, and quince) – fire blight.

What is Fire Blight?

Fire blight is a contagious, systemic, bacterial disease. Bacteria (erwinia amylovora) attack the blossoms in early spring and then move up the twigs and branches through the tree’s system. The name “fire blight” comes from the scorched appearance of the infected leaves, stems, and bark. These areas may appear black, shrunken, and cracked. Blossoms will turn brown, wilt, and die about 1-2 weeks after infection occurs.

Fire blight may also exhibit an amber-colored ooze (which is heavy with bacteria) from the bark of the tree. When the spring temperatures begin to climb between 60°-80°F, optimal conditions are created for spreading the disease and the bacteria is brought out of dormancy. Bees, insects, birds, splashing rain, and wind easily spread the bacteria and the resulting fire blight disease.

Fire blight commonly affects apple and pear trees (both fruit-bearing and ornamental types), but can also affect quince trees and other members of the Rosaceae family – including most common rose varieties and raspberry plants.

To avoid turning this into a science lecture*, letʼs move on to how to control fire blight.

Managing Fire Blight in Affected Fruit Trees

In high-pressure areas, your best defense is likely going to be a combination of cultural practices, cleanup, and manual/chemical control methods.

Cultural practices. Any excessive amount of new growth on your tree is easily susceptible to fire blight infection. To avoid this susceptibility to fire blight in your trees, especially if you live where fire blight is a known issue, it is recommended that you use a low-nitrogen fertilizer during the growing season (stopping before July) – and only fertilize when necessary. Fertilizers should only be used to supplement nutrients in soils that are lacking them.

Cleanup. Be sure to do a complete cleanup around your trees when fall rolls around. Collect all pruning debris, mummified fruit, and fallen leaves. Move them away from the trees and destroy them – do not add to compost! This will prevent the bacteria from overwintering in the debris and then spreading.

Manual control. Remove the blighted wood from infected shrubs and trees, as this helps prevent the disease spreading. Prune off all infected branches at least 8 inches below the blighted area (some experts even recommend pruning to 12 inches below blighted areas). Burn and destroy the affected branches if possible.

Because fire blight is highly contagious, take care to disinfect pruning tools. Sterilize the tools in a household bleach solution (ten parts water to one part bleach). Dip clippers between every cut. Be sure to wipe clippers dry to prevent corrosion.

Alternately, use alcohol wipes to clean your clippers between cuts instead of bleach solution. This will help protect your trees and your tools.

Chemical control. An approved fire blight spray can help control bacterial infections. It should be applied from bloom time through the spring storm period, following the product label.

Plant blight-resistant varieties of fruit or ornamental trees to help reduce risk of infection; however, you may still need to provide routine care and maintenance to control fire blight. This works in the best interest of your trees and helps to avoid spreading the infection to neighboring plants and trees. Get in touch with your local experts, like those who work for your cooperative extension, to help you diagnose and control an outbreak of fire blight in your area.

Remember: there’s not one single practice that will ensure complete control of fire blight, still I hope this information gives you a good understanding of fire blight and helps to make your fall, winter, and spring productive and manageable!

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39 Comments

In addition, Ag extension recommends using a basic copper sulfate solution in dormancy. Do you recomment that? and do you have a recipe for a basic copper sulfate solution.
Finally, I have a number of apple and pear trees from Starkbrothers. I lost a seckel pear to fire blight. Do you have a replacement variety of seckel pear that is more resistant to fire blight?

Hi Larry,
A copper sulfate spray is good in dormancy, but we usually recommend using a combination of Dormant Oil and Lime Sulfur during dormancy. This combination will kill fungus, and the dormant oil will smother any eggs that are laid. One thing that will really help with all insects and diseases is a thorough fall cleanup. After your tree goes dormant, remove all mummied fruit from the tree and the ground. Rake away all pruning debris and leaves from your fruit trees, then burn all of it!

Actually, the Seckel pear tree is moderately resistant to fire blight. Following a good spray schedule, and doing fall maintenance (pruning, clean-up) will certainly help keep your fruit trees insect and disease free.

I had this issue hit my apple, pear and raspberries. I tried to buy the Streptomycin spray to kill the bacteria and was told that it has been pulled off the market because of regulations. Do you know about this and if so what do we do now?

Hi Cynthia, boy, that is tough, having fire blight affect your trees! I don’t know if where you live the Streptomycin has been pulled off the shelves, but, we still carry Fertilome Fire Blight Spray (main ingredient: Streptomycin) and it has not been restricted to any states. Check your local garden store for Fire Blight spray. If you can’t find Fire Blight Spray, get a Copper Spray. That will work very well, also.

Good luck with your fruit trees! If anything else comes up, just give us a shout.

I by mistake got shipped a pear tree with several varieties of pear on the same tree. A couple varieties of the pears were very susceptible to fire blight. You really have to cut back and get everything out. I sprayed with a copper spray last fall and think it really helped. It was a pretty dry year too. I don’t think there is alot you can do if you have a variety that is very suspeptible to fire blight. I would cut the tree totally down but it’s a good poll. for other pear trees.

How about an article on Brown Rot. I think I have the most problem with Brown Rot on fruit and can you get Brown Rot on the bark of the trees?

One thing that helps a lot to slow any fungal disease is to do a complete fall clean up. After your tree goes dormant, remove all mummified fruit from the tree and the ground, and rake up all pruning debris and leaves. Then burn all of it! This limits potential for over-wintering fungal spores. Infections from fruit left on the tree may advance into the wood causing small cankers, so removing old fruit is important.

Stark could do an invaluable service for us small growers by showing a photo of some common bacterial/fungicidal diseases along with the most effective remedies. This kind of information is essential to being a successful small orchard owner.
Thanks for any assistance.

I am so sorry to hear about the loss of your plants and trees. It could be caused by infected soil, or it could be weather-related. If you were in an area that received a great deal of rain and had a very cool spring, that could cause a lot of problems as well. Your County Extension Agency will be able to help you with some good localized information regarding the weather’s affect on your plants and trees this year as well as a soil sample test to determine whether or not it is an issue with the soil.

I had a late hatch of San Jose Scale and it really made a mess couldn’t sell a 1/3 of the apples never had that happen.Apples ripened a month early here. I stopped spraying then all of a sudden there were all these scale flying around.I sprayed oil and lime sulfur this spring.but now I’m lost

Hello Ken! Control is aimed at the overwintering immature scales and at the San Jose Scale crawlers.

- Spray the tree(s) with Dormant Oil spray while the trees are dormant, ideally before buds swell in the spring.
- Be on the “look out” for crawlers to appear in the latter part of summer.
- Spray with an insecticide like Sevin when crawlers appear. You can also use Insecticidal Soap for a natural control, but it’s in a hand-held spray bottle, so it may not be ideal or effective for several mature trees or large infestations of scale.
- If there are recurring events later, you can use the same treatment method to rid your garden area of the scale.

I hope this information helps you rid your apple orchard of San Jose Scale!

I have a damson plum tree that has black, corky growths on several limbs, which I cut off but the growths still persist. What is this & can the tree be saved? Is it a danger to nearby peachtrees? thanx for your feedback:)

Hi Jim, I am so sorry for the delayed response, as I had the information & completely forgot to post it for you! Please accept my apologies.

It sounds like your plum tree has Black Knot (a disease we’ll be posting on in the near future). To control Black Knot, the important 1st step is pruning the infected branches & removing them from the growing area. (All black knot pruning should be done in late winter, before any new growth is present.)

Pruning debris (leaves, cut branches, mummied fruits) should also be removed from the growing area & immediately burned. The reason for burning? Knots are capable of reproducing & releasing spores, which will re-infect trees. We want to avoid that cycle. Removing all sources of infectious spores from the area is really necessary.

Also! …Fungicide spray can work defensively against black knot, but it won’t be very effective if the pruning & complete clean-up are ignored.

Again, I’m truly sorry it’s taken me a while to post this info for you! I hope it helps revive your plum tree. Best wishes, Jim!

Hi there, Steve. If you have been fertilizing your tree, I would recommend holding off on the fertilizer until your fire blight issues are under control. As the article states, the excessive new growth encouraged with fertilizers high in nitrogen will be susceptible to infection.

Prune out any and all infected limbs at least 6 inches below the visible signs of infection, cleaning/disinfecting the pruners between each cut (mandatory to avoid reinfecting the tree), burn anything you prune off so that it isn’t lying on the ground ready to reinfect your pear, and be sure to use something like Ferti-Lome® Fire Blight Spray, most effective during bloom time (which is when the trees are most likely to contract the bacteria). This will help to control the disease.

You did say the tree is “fully infected” so if it is that bad it may be beyond saving. If there is a chance it has not been overtaken by fire blight, it may take a lot of effort, but you should be able to save your tree. Your local county cooperative extension may have more advice and help local to your area, so I highly recommend reaching out to them!

I have two apple trees that I planted last year. The new leaves would curl up and turn brown. Also, some of the older leaves would do the same. I have been thinking that it was fire blight. However, the leaves and stems never turned black, only brown and withered. Someone told me that fire blight always turns the tips black. Is this true? I have a ton of new trees coming this spring, including other apples, cherries, plums, and peaches. I am wondering if I should just remove the two trees in question before my new shipment comes in or if it will be possible to save them.

Hello Glenda The best way to tell if your current trees are infected with fire blight (and aren’t suffering from something like a nutrient deficiency or mites instead) would be to see pictures of what you’re experiencing.

If you could please send photos to info@starkbros.com we will be able to better identify what is wrong with the trees. Be sure to mention whether the trees in question hold onto their brown leaves or if the leaves drop off the tree. It would greatly help us help you solve this!

Our two Thirty five foot Cleveland pears, exactly ten years old, are full of Fire blight. By the time I got any answers of what this condition was, There is no pruning back 12 inches to prune out the bad diseased starts. There are so many within inches of the main limbs that I am afraid it’s too late. Plus the fact of reaching the upper parts of the tree would be impossible without a bucket truck. We just are devastated about this, they are beautiful trees, almost perfect in shape and fullness and bloom so well. Our county ext. agent says Sprays do nothing to cure they just prevent. Pruning out is the only chance, and that is slim to none.

I’m sorry to hear your Cleveland ornamental pear trees have fire blight, Doug. Years ago it wasn’t found in ornamental pears but over time we have even found it in our own Cleveland pears growing here. Fire blight sprays are a control, not a cure, but (combined with the pruning the tree needs) it is the best bet for your trees.

I would recommend hiring a licensed tree professional to help if you are going to try to save your Cleveland pear trees, especially since they are so tall. It sounds like you care for your trees and I think it would be worth it to have them professionally tended to before giving up.

I have an apple tree in my small (8 tree) orchard that has black soot down the trunk..and assume this is fire blight…would you consider this tree a loss? should I just remove the tree? I also question 2 adjacent trees- the branches appear fine, but where the trees were pruned up along the truck appear to be black…should I hold off on adding any trees to the orchard this year?

Hi Erin! Since Fire Blight tends to present in the flowers/leaves/limbs of the susceptible trees, the fact that the trunk is the only thing with the sooty appearance leads me to believe it is not Fire Blight affecting your trees. If you could take some photos of the trees and the black soot appearance on their trunks [and send them to info@starkbros.com] we might get a better idea of what it is so that we can advise you accordingly.

It is very likely an easily treated fungal issue, so we look forward to confirming with your photos!

Hey everyone! My father is growing a bunch of Asian pear and sweet cherry trees on our farm in Pineville Missouri (southwest MO) and we’ve run across what seems to be a strange pest that we can’t identify.
It’s a styrofoam-like dark grey or dark brown shiny thumb-nail sized blob that attaches only to the smaller twigs on the trees and it wraps around the twigs almost completely but not entirely. It’s sort of crusted to the twig and the underside seemed to had little circles which could potentially be seeds or spores or something. There are often multiple twigs infected per tree and each twig that is infected generally has more than one of these small whealts. The things can be removed manually with relative ease.
The Asian pear trees seem uneffected but still infected by their presence but the sweet cherry trees seem to be suffering, but it could just be due to heat stress and the Japanese beetles.
Any help identifying or treating would be appreciated! Thanks!

Hi there! I am very curious about this occurrence you’re seeing on your cherry trees, Jakeru. It sounds like it could be where a pest laid eggs, and what you’re seeing is the nest wrapped around the twigs. Easter Tent Caterpillars are known for doing this, as you can see here.

Hi Greg – Our experts advise that you follow the directions printed on the labels for specific timing, but generally, since you use the fire blight spray during your trees’ bloom time (when you’re NOT spraying a pesticide), you would use that first. The first application of a pest control during the growing season wouldn’t happen until AFTER all of the blooms have fallen, so their timing won’t exactly overlap, but you can theoretically use both – just not at the same time.

Hello we have 5 Asian pears of different varieties from Stark Brothers that are doing great. One gets fire blight but it can be controlled. However we bought a Wine Sap and Granny Smith from the local big box store and both succumbed to fire blight last year. My question is can I plant over the old trees (with Stark Bro trees of course, learned my lessons the hard way) or is the ground toast and the new trees will also develop fire blight?

Hello Hamid! Fire Blight is a bacterial disease that is systemic and very contagious. It’s not something that is restricted to the soil of the planting site where infected trees once grew – but when replacing trees, it’s usually best to use a new planting hole rather than reusing an old one, just to avoid any potential issues.

The best thing you could do, since you know fire blight is problematic there, would be to plant blight-resistant apple varieties (like Enterprise Apple along with a Fire Blight Spray), but if you’re really looking forward to growing Winesap and Granny Smith apple trees, you can try to prevent the disease with a fire blight spray and through pruning and sanitization – especially during cool, wet growing seasons.

Another thing to should consider is contacting your local County Extension and inquiring about recommended fire blight control there.

Hi, I have a Plum tree w/fireblight. the cankers are on the branches, but, I am seeing the beginning of cankers developing in the trunk. I will cut it down today. I do have, however, lots of fruit trees and would like to save them! and I have more fruit trees coming in from Stark Brothers. I also have two Asian plums, multiple Asian pears, lots of other pears and cherries and apple trees. I want to plant another fruit tree in the plums place—What can I plant? How to prevent close lying trees from getting infected? does Stark sell and all in one preventive spray, and also what is safe for the bees and birds? will this copper sulfate you mentioned earlier harm the drinking water? I am on a well, but, also am concerned for the wildlife. how do I prevent fireblight on my other trees and preserve the ecosystem, bees and birds and other animals as well. does stark sell any of this stuff? what should I buy? and how to maintain. I have thousands of dollars in plants and trees, and I hate to lose everything. the plum was planted in sandy, well draining soil, was not fertilized more than throwing a handful of Osmocoat on the peonies in the spring. if I remembered. it grew fast, by itself. was facing south, was protected from wind by a semi-dwarf Bartlett pear about 15 to 12 feet away from it. I had no idea that the Asian pears, I have several three in one Asian pears, and I bought 3 in one cherry tree and four in one apple, plus the usual assortment of peaches, pears-seckel, Anjou, Comstock, keiffer, etc. how to protect all of these and where on earth did this disease come from. I am the only one with fruit trees in my immediate area, other than some older apples trees which I have and a neighbor. it’s wild or farm out here. please advise before I order more fruit trees from stark brothers. thanks, natasha –ps. other fruit trees also on sand or else in heavy clay, it’s one of the other.

Well, the “good news” is that your plum tree didn’t have fireblight, since plum trees are not affected by that particular bacterial disease. However, if it had bacterial canker, it was likely initially caused by a cool wet spring, and the bacteria probably stayed dormant through the summer, fall, and winter, to emerge and spread the following spring.

Bacterial canker is difficult to control if it’s already there, but more easy to avoid in the first place. Trees that have a good foundation and healthy soil are more vigorous and tend to be more resistant to the bacteria. Fertilizing helps, but the “right spot” is always preferable. Copper-based fungicides are said to help, but the best thing you can do now is have your plum tree’s issue professionally identified.

It’s impossible to advise what steps to take if you don’t know for sure what the tree was suffering with. If you have any photos of the plum tree with cankers, or if you have not yet removed the tree, your local county extension should be a great help in identifying the issue. They can also help in recommending what you can do to protect your other fruit trees (in case they are at risk) and what you should do to avoid this happening again.

Bacterial canker tends to target young “prunus” fruit trees, which includes cherries, peaches, nectarines, apricots, and of course plums. The same bacteria won’t affect your apple and pear trees, but you should probably not plant any new trees in the same planting hole as the plum you cut down just as a general rule. I also recommend getting the issue properly diagnosed by your local experts before trying to plant something else, just to be safe.

Elderberry plants growing in high-moisture areas may show signs of fungal disease. Without me having a photo to look at, I can’t speak for certain what the spots are, but brown spots are often a sign of a fungus.

Remove and destroy the spotted leaves and stems and you can try using a fungicide (multi-purpose or even natural) and see if it helps clear up the issue.

Does fire blight affect walnut trees? I have a Kwik-Krop Walnut planted in Fall of 2012 that is starting to have some leaves that turn brown or black starting near the tip and eventually curl and fall off. It has been a very cool and wet Spring this year. I need to know how to treat this.

Fire blight mostly affects trees like apples and pears (even ornamental ones), but not walnuts/black walnuts. What you’re seeing is more than likely a fungal disease, like leaf spot, but you may be better off contacting your local county cooperative extension for more localized advice — I don’t want to suggest that it’s a fungal disease when it might actually be something more serious and viral, like walnut anthracnose, in the area.

If you are able to determine that it is a fungal disease, your tree may be able to go without treatment (if it’s too large to spray), since it will mostly affect a few leaves. You can try a nut-tree-friendly fungicide like this spray if your tree is still small enough to manage the fungal disease.

Fireblight tends to affect specific limbs — usually ones that bloomed or had injury where the disease got into the tree — so it is possible for a tree that has fire blight to also have some unaffected limbs/fruit. In this case, the fruit will be edible; however, if you have treated your trees with a spray to fight the bacteria that causes fire blight (one that contains streptomycin or something like that), it is recommended that you don’t eat the fruit from the tree the same year that you’ve sprayed fire blight spray.

I have planted 6 apple trees from stark one year ago and some this year to round out the 6 trees. All the trees have fire blight and have since they were planted. It has to be the ground, it happened very soon after planting. I have done everything I could find to do, ending the season with a 7 day spray schedule alternating with copper and neem and another spray I cant remember. As you can imagine this was very time consuming and tiring for an old man. The leaves have not yet dropped and I don’t want to clean up until they do. I cant go through this next season, I guess the blight won unless you have a way out. Thanks!!!!